Molding apparatus



Dec.8, 1959 H.-Z.GORAI "2,915,784

Y MOLDING APPARATUS ori inal Filed April 17, 1952 I 4 Sheets-Sheet 1 lllll u IN VENTOR fi e/74y Z. 60rd B'Y ATTORNEYS Dec. 8, 1959 z, o RA vMOLDING APPARATUS Original Filed- April '17. 1952 4 Sheets-Sheet 2 1NVENTOR ffe/r/jy Z (fa/ a ATTORNEYS INVENTOR MAM ATTORNEYS 4 Sheets-Sheet3 H. z.' GO RA MOLDING APPARATUS mw mm 3. mN. mm 3 Hefl/y 60% BY W Dec.8, 1959 ori inal Filed April 17. 1952 United States Patent MOLDINGAPPARATUS Henry Z. Gora, Stratford, Conn., assignor, by mesueassignments, to The Eagle-Picker Company, Cincinnati, Ohio, acorporation of Ohio Original application April 17, 1952, Serial No.282,795, now Patent No. 2,864,123, dated December 16, 1958. Divided andthis application July '17, 1956, Serial No. 598,479

14 Claims. (Cl. 18-20) This invention relates to an apparatus formolding articles of plastic material and constitutes a division of myco-pending application Serial No. 282,795, filed April 17, 1952, nowPatent 2,864,123 of December 16, 1958.

In my prior Patent No. 2,548,306, dated April 10, 1951, there isdisclosed the method of molding articles including the steps ofplasticizing material, producing an endless strip thereof, and passingthe latter between pairs of cooperating die members which blank materialfrom the strip and mold it to shape. When, as illustrated in saidpatent, the dies are on the periphery of adjacent drums, the time duringwhich the cavity of each die is closed is extremely short (when theapparatus is operated at practical speeds) with the result that thematerial is not subjected to the heat of the dies long enough topermanently set it in shape, and slight distortions of the article occurwhile they are being cured out of the die cavity, in a curing oven forinstance. For many kinds of articles, such as nail washers, garterbuttons, etc., such distortions do not interfere with the properfunctioning or use of the article.

To permit more precise molding of articles, I have devised methods andapparatus in which the material is kept in the heated die cavity for arelatively longer period of time. This is accomplished by providing aseries of pairs of axially aligned die members traveling in a closedpath (being mounted on a carrier such as a wheel or drum for instance),guiding a strip of plasticized material longitudinally into a spacebetween the open die members, and then closing the die members on thestrip to blank out and mold a portion of the strip in the heated diecavities which are closed during more or less of the travel of the diemembers in their cycle of movement to set the material to desired shapeand size.

One species of my invention is disclosed in my Patents Nos. 2,593,438and 2,593,668, granted April 22, 1952, in which the die members areclosed on the strip of molding material and remain closed carrying theimpaled strip along with them until the die members are separated andthe articles discharged therefrom. For certain articles and undercertain conditions this method is efiicient and high production can beobtained with relatively inexpensive apparatus.

In another species of my invention, that disclosed and claimed herein,by making a larger carrier or wheel and increasing the number of pairsof die members and thus prolonging the time during which the material inthe die cavity is subjected to heat and pressure, withoutproportionately reducing the production rate, I am able to produce insatisfactory quantities molded articles more precise and uniform thanhas heretofore been possible with multicavity platen molding, albeit theapparatus costs more to produce than that shown in my above mentionedpatents, but a greater variety of precision molded articles may beproduced by its use.

In the hereindisclosed apparatus, the strip of plasticized enough tobring the die members together on the strip I through themolded article.material follows the path of the die members for only long I 2,915,784Patented Dec. 8, 1959 ice and blank out therefrom a quantity of thematerial and deposit it in the die cavity. Within a short time the diemembers are separated and the strip is guided out of the path of the diemembers leaving the blank in one of the cavities. This has the practicaladvantage of avoiding the partial curing of the skeletonized strip whichwould occur in prolonged contact with the heated die members and thusthe strip may remain reusable. After the strip is removed, the diemembers are closed under resilient yielding pressure and the blank orslug in the cavity responds to the heat of the die members and flows tofill the cavity and in its prolonged confinement in the cavity becomessemicured to a degree Where, upon discharge from the cavity and furthercuring in an oven, the article will maintain its desired shape and size.

The duration of this semi-curing operation depends on the kind and theformulation of the material used, the volume of the piece molded and itsthickest cross-section, and the temperatures to which it may be exposedwithout scorching. The size of the apparatus, i.e. the length of thepath of the die members and their speeds of travel, may be calculated toobtain satisfactory semi-cure at the desired economically efficient rateof production.

The thickness of the plastic strip (controlled by the warming millrollers in the embodiment of the invention herein illustrated) ispredetermined to produce a blank or slug having a mass beforeresponding'to the prolonged heating effect of the die members slightlyin excess of that needed to fill the cavity and form the desiredarticle. With many kinds of articles the contacting surfaces of thecavity forming parts of the die members are'capable of removing from astrip of practical or optimum thickness a blank of the desired mass.

I have found it advantageous to relieve the pressure of the die memberson the blank one or more times after the blank is initially formed bythe dies to permit the escape of any gas or air which may be trapped inthe cavities and to permit excess material to easily flow past thecut-off surfaces. Such excess material remains attached to the strip andis removed therewith.

I have also devised an eflicient mechanism for opening, closing andholding the die members closed whereby each pair of die members isindividually controlled both as to their positive action and theirresiliently yielding action.

The die members are preferably carried by a heated portion of thecarrier or drum while the operating mechanism therefor is carried by aportion of the carrier which is not intentionally heated and preferablyshould be as cool as possible to maintain the parts properly lubricated.I have devised a unique way of securing these two carrier or drum partstogether in poor heat conducting relation. These and other features andadvantages of the present invention will be described below.

In the accompanying drawings:

Figure l is a side elevation, partly in section, of the apparatus of thepresent invention. 3

Fig. 1A is a diagrammatic view showing the outline of the cams forperforming the various operations. 7

Fig. 2 is a plan view of the apparatus, also partly in section. i

Fig. 3 is a fragmentary sectional view taken through the drum andshowing the cooperating die members and the associated operating unit indie-closing position.

Fig. 4 shows the die members and-the operating unit in position with themovable die member retracted.

Fig. 5 is an enlarged view of the operating ends of the die membersshowing one way of producing a 'hole clean Fig. 6 is a plan view on alarger scale than Fig. 2, ,of two adjacent operating units showing onein section.

As shown in the accompanying drawings, the apparatus of the presentinvention comprises a frame at one end of which is mounted a pair ofmill rollers 11 and 12 on which a quantity of moldable material such asrubber or similar material may be plasticized and form on the roller 12an enveloping layer 13 of determinate thickness controlled by thespacing between the mill rollers. Cutters 14 remove from the layer 13 astrip 15 of determinate width, the void resulting in the layer 13 beingconstantly filled by migration of the material in the bank so that thestrip 15 is continuous so long as the bank is mairr tained and themachine is operated.

At the other end of the frame there is a carrier or drum-like structure16 mounted on a horizontal shaft 17 and rotatingly travels in a verticalplane. The carrier or drum 16 is formed of two parts 13 and 19, the part18 having spokes 20 extending from a hub 21 and the part 19 being in theform of a ring carried by the part 18. The part 19 has removably mountedon its periphery a series of operating units 22 closely spaced and eachincluding a cam follower 23. Secured to the frame and overlying the drumpart 19 for a large arc of the latters movement is a cam support 24 onwhich a plurality of cams are adjustably mounted in position to beengaged by the followers 23 as the drum rotates. Mounted on the part 29of the dnim is a series of pairs of coaxially aligned die members and 26which may be separated and brought together.

As shown, the die members 25 are mounted to move axially toward the diemembers 26 and each is connected to an axially aligned operating unit 22by which it is operated when the cam follower 23 reaches and is operatedby the cams on the cam support 24 during the rotation of the carrier ordrum. The die member 26, in the embodiment of the invention hereinillustrated as exemplary thereof, is mounted so as not to be movable formolding purposes.

In the open position there is a space between the die members 25 and 26and it is into this space that the strip 15 is guided from the millroller by guides 23a, 28b, 28c and 2841 set at such angles that thehorizontally disposed strip is twisted to lie in a vertical plane and toenter the space 27 between the die members substantially tangentially tothe path of the die members. When so located, movement of the die member25 to closed position engages the strip 15 and presses it against thedie member 26 with sufiicient force to sever a blank 2) from the stripand deposit it in the die members. At the same time the strip 15, whichis somewhat wider than the working ends of the die members 25 and 26, isimpaled on the die member which penetrates it and is carried around withthe drum by the die member. When the material being molded is to besemi-cured, the die members 25 and 26 are heated by conduction orotherwise through their supporting means in a manner hereinafterexplained.

According to the present invention the strip 15 is carried along withthe die members only so long as is necessary to control the strip andpartially form the blank. Hence the die-closing cam 30 is of such lengthand so positioned that after a few succeeding die members have impaledthe strip 15, the movable die member 25 recedes and opens the spacebetween the die members and the strip 15 is stripped from the die member25 by a stripper after which the strip is guided from the path of thedie members by guide rollers 32, 32a and is traveled back to the bank onthe mill rollers to there commingle with the bank, the strip beingassisted in its return movement by power driven feed roller 33 andpressure roller 33a engaging it.

By thus quickly removing the skeletonized strip 15 from the die membersthe danger of partially curing the material of the strip by prolongedcontact with the heated die members is avoided and the strip is returnedto the mill at substantially the same temperature as that at which itleft.

The short period during which the die members are closed to form theblank is not always sufiicient to set, or in the parlance of the antkill the nerve of the material, and precision molded articles are notthus produced although for making such articles as nail washers, garterbuttons, etc. it is sufficient and the articles can be immediatelydischarged from the molding cavity.

However, according to the present invention in order to performprecision molding, as soon as the strip 15 is removed, leaving the blankin the cavity of one of the members, the die member 26 in the formshown, the movable die member is again moved to cavity closing positionby another lobe on the cam 30 so that the blank may be subjected to heatwhile confined in the molding cavity between the die members 25 and 26for a prolonged period sufficient to cause the material to flow and fillthe cavity (and overflow if necessary during its heating up) and becomesemi-cured to the degree in which it will maintain its shape and sizeafter being discharged from the die cavity and may be, as taught in myprior Patent No. 2,548,306, completely cured or vulcanized in an oven.

According to the present invention in its preferred form the article isnot discharged from the die members 25 and 2-6 until the die members areopened to receive the strip 15, since, considering the speed of thedrum, if the semi-curing step should require less time than is requiredto bring the article curing dies to open stripreceiving position thespeed of rotation of the drum may be increased, thus increasing the rateof production.

As is the practice in conventional molding processes the timing of theoperations should take into consideration the usual factor including thekind of material used, its formulation, the volume of the article, themaximum cross-sectional thickness thereof, the hardness desired and thesafe temperatures at which the material may be processed.

After the die members are closed on the blank the latter expends andtends to overflow the cavity, escaping past the cutoff surfaces 34 atthe parting line of the die members. This is permitted, according to thepresent invention, when the pressure within the cavity reaches adeterminate value by the yielding of a spring 35 in each operating unitwhich, as hereinafter explained, permits the movable die member to backoff slightly from the fixed die member. When the pressure is releaseddue to the escape of the material, the spring 35 returns the movable diemember 25 to the fixed die member 2-6 and the overflow of the materialin the cavity is cut-0d.

To facilitate the escape of excess material when the blank is initiallyformed, the cam as is positioned and shaped to retract and advanceslightly the movable die member 25 one or more times as the heating ofthe blank progresses, the cam 36 having undulations 37 for this purpose.The repeated opening and closing of the molding dies by the cam 36 alsoaffords an opportunity for air or other gases which might be trapped inthe cavity to escape and the excess or overflow material is allowed toremain attached to the strip 15 which during these repeated retractionsis still carried along with the die members.

After the cavity is opened by retraction of the movable die member 25just before the next blank is formed the molded article is ejected fromthe fixed die member 26 carrying it. At the time the die member 25 is retracted any flash material between the contacting or cut off surfaces ofthe dies is free to fall away as the molded article is ejected. Anyflash material clinging to the molded article is readily separatedtherefrom in a tumbling operation since it is extremely thin and onlyloosely attached. For the purpose of so ejecting the article the fixeddie member 26 is provided with an axially disposed ejector plunger 38having an extension 39 to be engaged by a cam 49 carried by the frame ofthe machine. As the drum :6 revolves the extension 39 on the ejector 33engages the cam 40 and the article within the fixed die is pushed fromthe cavity. The ejected article falls through the space between the diemembers 25 and 23 and between the spokes 18 of the drum onto a chute 41which guides it to the end of a conveyor belt 42 within a tunnel 43. Thetunnel 43 is heated to vulcanizing temperature and the belt is traveledat such a speed that by the time a molded and semi-cured piece reachesthe end of the tunnel it will be vulcanized.

The operating unit 22 comprises a separate subframe or housing 44, thebase of which is removably secured in a keyway 19a by bolts 45 to thepart 19 of the drum in substantial alignment with the axis of the diemembers 25, 26. As shown in Fig. 3 a dowel pin 45 locates the housing 44in the keyway 19a in proper position to receive the fastening screw 45.

The upper portion of the housing 44 has a guideway 46 to receive a slidebar 47 carrying a cam follower roller 23 for engagement with the cam 30carried by the cam support 24 mounted on the frame. The lower part ofthe slide bar 47 carries a block 48 having a vertical slot 49 in whichrides a roller 50 on a bell crank 51. The bell crank 51 has a pin 52carried by a bar 53 constituting the relatively fixed pivot point of thebell crank. The bell crank 51 has a pivotal connection 54 with a link 55pivotally connected at 56 to the die member 25 which reciprocates in aring 64 forming part of the drum part 18. When the slide bar 47 is inthe position shown in Fig. 4 the die member 25 is retracted and when itis moved by one of the cams to the right as shown in Fig. 3, the diemember 25 is advanced and the pivotal connections 52, 54 and 56 betweenbar 53, the bell crank 51 and the link 55 are brought into alignment sothat any force tending to push the die member 25 to open position willnecessarily have to move the pivot point 52 for the bell crank, sincethe latter and the link constitute a toggle which is locked in theextended or cavity closing position of the die member. Preferably,.thebell crank 51 shows its pivotal connection 54 with the link 55 slightlybeyond a straight line drawn between the pivot point 52 and the pivotpoint 56 on the die member 25 Where it comes to rest against an abutmentsurface 58. In this position the toggle is self-locked and will remain'so without the follower roller 23 engaging the cam 39, and thus theload of keeping the toggle locked does not have to be sustained by thestationary cam with the resulting continuing work and friction, but issustained entirely by the drum 16 which, of course, rotates with theoperating unit. To unlock the toggle, the follower roller 23 is engagedby cam surfaces 59 on the other side of it to move it to the left asshown in Fig. 4.

To maintain the die cavity closed under yielding resilient force, therod 53 on which the pivot point 52 for the bell crank 51 is mounted isslidably mounted in the housing 44 of the unit. The end of the rod has ahead 60 extending beyond the housing and normally engaging it to limitthe inward movement of the rod. Engaging the head is the coil spring 35,the other end of which engages a head 61 mounted on a screw 62 threadedin an extension 63 of the housing 44. When the die is closed, any forceacting to open it, for instance the expansion of the material containedwithin the die cavity, is transmitted through the link 55, bell crank 51and pivot point 52 to the rod 53, which may be moved under the yieldingresiliency of the spring 35. When the force is released the spring 35,acting through the parts just named, will return the die member 25 tocavity closing position. The same action takes place when the die member25 is initially closing on and penetrating the strip 15 of moldingmaterial, for if the resistance to penetration is too great consideringthe speed of movement, the spring 35 will initially yield and thenreturn to its normal position when the material has had suflicient timeto squeeze out from between the movable and immovable die members. Thespring 35 also permits the slight recession of the pivot point 52 of thebell crank when the connecting pivot 54 between the bell crank 51 andthe link 55 passes over dead center.

It will be noted that when the dies are closed there is a space betweenthe head 60 and the adjacent surface 44a of the housing 44 as shown inFig. 3. However, when the dies begin to separate and pressure is removedfrom the rod 53, the head 60 engages the surface 44a of the housing 44as shown in Fig. 4 and thus the parts of the toggle mechanism arerelieved of the spring load.

Thus it will be seen that the spring 35, besides acting as a safetyfeature to prevent damage to the die members which might be caused bypressing them together with unyielding force, also serves asa follow-updevice to close the dies when the resistance to the movement of themovable die ceases.

The operating unit 22 herein described, it will be noted comprises aunitary assembly which is removably connected to the carrier and whichwith the die member 25 and connected rod 53 may be completely and bodilyremoved from the carrier by simply removing bolts 45 thus permitting theunit to be slidably removed from the carrier at some point where roller23 is free of the cam 30; e.g. at the 3 oclock position of the drum inFig. 1. As a result repair or replacement of the unit is greatlyfacilitated.

It will be observed from Fig. 3, that rings 63 and 65 on the part 18 ofthe drum carry the fixed and relatively movable die members and thatthese have chambers 66 which are connected by pipes 67 to a swivelconnection for steam or other temperature controlling fluid. Whenmolding rubber or other thermoplastic material, steam is used and therings become hot. To avoid conduction of heat from the major portion 18of the drum to the part 19 carrying the operating units 22, the actualphysical contact between the part 18 and the part 19 is reduced to aminimum. This is accomplished in the apparatus illustrated by having asmall portion of a flange 68 on the part 19 fit within the ring 64 onthe part 18 to locate it and passing bolts 69 through lugs 70 on thering 64 into holes in the flange 68, spacing washers 71 being interposedbetween the ring and the flange to further reduce the area through whichheat may be conducted from one to the other. This enables the operatingunits to be lubricated without the difliculties caused by hightemperatures.-

To permit the rapid conversion of the machine from the manufacture ofone product to that of another of different size or shape, the movabledie member 25 includes a removable die head 72 which may be secured inthe main body ofthe die member 25 by means of a locking screw 73 whilethe fixed die member 26 is itself removably mounted in the ring 65 andis held in its position by a locking screw 74. Thus, either the die heador the immovable die member or both may be removed by merely looseningthe set screws holding them in place, slipping them ofi their supports,and substituting other parts and holding them in place by tightening theset screw.

To solve the problem of molding elastic articles with a clean holetherethrough (such as the screw hole in the center of a bibb washer),the present invention provides a hole-forming rod or projection 75 inone of the die members with a recess 76 in its end, leaving only a verynarrow cut-off surface 77 defining the inner wall of the hole to beformed. When the die members are closed and the rod abuts its opposingsurface 38a on the other die member, the molding material unavoidablylying between the cut-off surface 77 at the end of the rod and itsabutment is squeezed out leaving the hole, when the die members areseparated, open clear through with little or no flash clinging to themargin of the hole.

The material lying inside the cut-off surface 77 may either be squeezedout by application of yielding pressure or may be retained within therecess 76 to be disposed of in some way.

As illustrated in Fig. 5, the recess 76 in the rod communicates with apassage 79 extending through the die member to an outlet 80. By thisarrangement, molding material trapped within the cut-01f surface 77 isforced through the passage 79 accumulating until it projects through theoutlet as an extrusion where it is knocked oif by a finger 81 (Fig. 1)located in the path of the die members.

Variations and modifications may be made within the scope of the claimsand portions of the improvements may be used without others.

I claim:

1. A toggle unit for operating a movable die member of a pair of axiallyaligned relatively movable die members cooperating to form an article,said die members being movable between open and closed position, saidtoggle unit comprising a housing mounted on a structure supporting thedie members, a pair of connected toggle links mounted in said housing,one of said links being pivotally connected to said movable die member,resilient means in substantial axial alignment with said die members andassociated with said other link to yieldingly resist movement of the diemember in opening direction when the links are locked during the formingof an article and to resiliently close the die members when resistanceto closing movement has dissipated, said resilient means including meansto relieve said link members of the load exerted by said resilient meansin open die position so that said link members are provided with adesirable amount of play in open die position, and operating meansslidably mounted in said housing for reciprocation therein and connectedto one of said link members for moving said toggle links so that saiddie members are closed and said links are locked in die closed position.

2. A toggle unit as in claim 1, having means for adjusting theresiliency of said resilient means.

3. A toggle unit as in claim 1 in which said resilient means includes abar pivotally connected to the end portion of said other link forslidable reciprocating movement in said housing in axial alignment withsaid die members and a spring fixed to said housing and operablyengaging said bar to yieldingly resist opening movement of the diemembers which is transmitted through the links and bar member to saidspring and to resiliently close the die members when resistance toclosing movement has dissipated, said spring being adjustably mountedfor varying the yielding resistance thereof.

4. A toggle unit as in claim 1 in which said operating means includes aslide bar slidably mounted in said housing for reciprocation therein, afork member mounted on said slide bar for movement therewith, saidmember being operably connected to one of said links and a cam followerfixed to said bar for engaging operating cams whereby said bar isactuated to move said toggle links into self-locking position when thedie members are closed.

5. A toggle unit as in claim 1 wherein said toggle links in locked dieciosed position are out of axial alignment with one another and abuttinga portion of said housing to prevent axial displacement of said links bythe opening pressure of said die members.

6. A toggle unit for operating a movable die member of a pair of axiallyaligned relatively movable die members cooperating to form an article,said die members being movable between open and closed position, saidtoggle unit comprising a housing removably mounted on a structuresupporting the die members, a pair of connected toggle links mounted insaid housing, one of said links being pivotally connected to saidmovable die member, a bar pivotally connected to the end portion of saidother link for reciprocating movement in said housing in axial alignmentwith said die members, means fixed to said housing for operably engagingsaid bar to yieldingly resist axial movement of the same under theopening pressure of said die members and to resiliently close the diemembers when resistance to closing movement has dissipated, means foradjusting the yielding resistance of said resilient means, means forrelieving said toggle link members of the load exerted by said resilientmeans in open die position so that said links are provided with adesirable amount of play in open die position, a slide bar slidablymounted in said housing for reciprocation therein, said slide bar beingsubstantially parallel the axis of said die members, a fork memberconnected to said slide bar for movement therewith, said fork memberbeing operably connected to one of said toggle links and a cam followerfixed to said slide bar for engaging operating cams whereby said slidebar is reciprocated to move said toggle links by means of said forkmember into selflocking position, said toggle links being moved pastcenter position into abutting relation with a portion of said housing.

7. An apparatus for molding articles of plastic material comprising arotatable drum; a plurality of pairs of axially aligned die membersrelatively movable between opened and closed positions mounted on thedrum in closely spaced relation and movable by said drum successivelypast charging and discharging stations; means for guiding a continuousstrip of plastic molding material between the die members in openedposition at the charging station; and means for closing the die memberson the said strip at the charging station to blank a portion of thematerial of the strip therefrom and for opening the die members at thedischarging station for discharging the molded articles from the diemembers, one of each pair of die members being relatively stationary andthe other being movable and each movable die member being actuated by anoperating unit mounted on the rotatable drum and including a togglemechanism which is self locking in die-closing position.

8. The apparatus as defined in claim 7 in which the toggle mechanismincludes a follower, and there are fixed cam surfaces which, as the drumrotates, are engaged by the follower intermittently to operate thetoggle to open and close the die members.

9. The apparatus as defined in claim 8 in which the cam surfaces areshaped for repeatedly and momentarily opening and closing the diemembers on the fresh blank therein.

10. The apparatus as defined in claim 7 in which the toggle mechanism isspring-backed to yieldingly resist opening movement of the die membersunder the force of expansion of the blank therein when heated and toresiliently close the die members when the opening force has beendissipated.

11. The apparatus as defined in claim 7 in which the toggle is mountedfor bodily movement away from dieclosing position in self-lockingcondition, and a spring is provided to resiliently resist forcefulbodily movement and return the toggle to die-closing position when saidforce is dissipated or removed.

12. The apparatus as defined in claim 8 in which the cam surfaces are oncam plates and there is a fixed stationary support following the contourof the drum and spaced therefrom, and means for adjustably securing thecam plates to said support.

13. Apparatus for molding articles of plastic material comprising arotatable drum; a plurality of pairs of axially aligned die membersrelatively movable between opened and closed positions mounted on thedrum in closely spaced relation and movable by said drum successivelypast charging and discharging stations; means for guiding a continuousstrip of plastic molding material between the die members in openedposition at the charging station; and means for closing the die memberson the said strip at the charging station to blank a portion of thematerial of the strip therefrom and for opening the die members at thedischarging station for discharging the molded articles from the diemembers, each means for opening and closing the die members beingmounted on a separate subframe removable from the drum for replacementand repairs.

14. An apparatus for molding articles of plastic material comprising arotatable drum mounted within a relatively stationary cam track, aplurality of pairs of axially aligned cavity forming die membersrelatively movable between open and closed positions mounted on the drumin closely spaced circular relationship and movable by said drumsuccessively past charging and discharging stations; means for guiding acontinuous strip of plastic molding material between the die members inopen position at the charging station; an individual toggling unit foractuating each pair of relatively movable die members mounted on saiddrum and movable therewith, said unit including a pair of pivotallyconnected link members mounted in said unit, the end portion of one ofsaid links being operatively connected to one of said die members;operating means connected to one of said links for moving the links intolocked position when the die members are to be closed, said operatingmeans having a cam follower for engaging the cam track as the said drumrevolves to successively operate the toggling unit to close the diemembers onto said strips to blank a portion of the material of the striptherefrom and deposit the blank in the cavity between the die membersand mold the article, and to open the die members at the dischargestation of the drum for discharging the molded article from the diemembers, and a yielding means fixed to said unit and connected to theend portion of the other said link member to yieldingly resist themovement of the die members in opening direction when the links arelocked during the blaking and forming of an article between the diemembers and to resiliently close the die members when the resistance toclosing movement has dissipated.

References Cited in the file of this patent UNITED STATES PATENTS977,687 Todt Dec. 6, 1910 1,368,836 Priester Feb. 15, 1921 1,525,629Thompson Feb. 10, 1925 1,633,317 Derry June 21, 1927 1,711,978 WandersMay 7, 1929 1,965,732 Blisterfield July 10, 1934 2,027,915 Kux Jan. 14,1936 2,055,742 Burk Sept. 29, 1936 2,058,880 Hunt Oct. 27, 19362,132,788 Hunt Oct. 11, 1938 2,624,915 Corson Ian. 13, 1953 2,657,426Gora Nov. 3, 1953 2,711,567 Knapp June 28, 1955 a UNITED STATES PATENTOFFICE CERTIFICATE OF CORRECTION Patent N0u Decemb'ar 1959 Golumn 5,line 39, for "shows." read throws 3 column linfi, for "An apparatus"read Apparatus column 10, line 7,,, i0r read blanking L Signed andsealed this 31st day of May 1960., (SEAL) Attest:

KARL 1-1. AXLINE ROBERT C. WATSON Attest ing Oflicer Commissioner ofPatents

